Solar Terrestrial Activity Report

Activity chart

Last major update issued on February 8, 2024 at 04:25 UT.

Charts (* = updated daily) Data and archive
  Solar wind (*) Solar and geomagnetic data - last month (*)
  Electron fluence (*) Archived daily reports and monthly data since 2003.01 (February 4, 2024)
Solar cycle Solar cycles 23-25 (February 1, 2024) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (February 1, 2024) Noon SDO sunspot count 1K image / 4K (*)
  Solar cycles 1-24 (July 1, 2020) POES auroral activity level [October 2009 - December 2012]
  Comparison of cycles 21-25 (February 1, 2024) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (February 1, 2024) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (January  3, 2024) Cycle 25 spots (final update December 25, 2019)
  Solar cycles 24-25 transition using 365d smoothing Research: Solar Cycle 25 Started on November 17, 2019 with 365 Days Smoothing
Calculating the Strength of Solar Cycle 25 Using 365-day Smoothing

Recent activity

The geomagnetic field was quiet on February 7. Solar wind speed at SOHO ranged between 445 and 540 km/sec. The high latitude magnetometer at Andenes recorded very quiet levels. The above 10 MeV proton flux was at background levels at the end of the day.

Solar flux density measured at 20h UT on 2.8 GHz was 188.4 - decreasing 4.1 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 157.34. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 158.71 on June 27, 2023). The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 3.9). Three hour interval K indices: 01121111 (planetary), 00112321 (Boulder), 01100001 (Andenes).

The background x-ray flux is at the class C1 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 14 active regions using 2K resolution (SN: 317) and in 13 active regions using 1K resolution (SN: 230) SDO/HMI images.

Region 13567 [N20W40] was quiet and stable.
Region 13570 [S02W32] was quiet and stable.
Region 13571 [S17W16] decayed slowly and quietly.
Region 13572 [S12W61] decayed slowly and quietly.
Region 13574 [N17W05] was mostly quiet and stable. The region has reversed polarities.
Region 13575 [S37W84] was mostly quiet after the major flare early in the day.
Region 13576 [S15E29] still has magnetic delta structures in the complex and spot rich leading spot section, a major flare is possible. C1 flares: C1.9 @ 01:13, C1.7 @ 22:54, C1.6 @ 23:19 UT
Region 13577 [N24W03] was quiet and stable.
Region 13578 [S04E41] decayed slowly and was mostly  quiet. The region has reversed polarities. C1 flares: C1.7 @ 00:36 UT

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9401 [S20W02] was quiet and stable.
S9404 [S14W74] decayed slowly and quietly.
S9407 [S16W57] was quiet and stable.
S9408 [S10E48] was mostly quiet and stable.
New region S9409 [S21E83] rotated into view with a mature spot.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.5 00:05   13575 GOES16  
C2.1 01:07   13575 GOES16  
C2.5 01:24   13575 GOES16  
C4.5 02:02   13575 GOES16  
C4.0 02:12   13575 GOES16  
C8.2 02:31   13575 GOES16  
C4.5 02:56   13575 GOES16  
M5.1 03:31 S38W74 13575 GOES16 CME, LDE
C5.7 05:58   S9408 GOES16  
C3.1 07:22     GOES16  
C2.3 08:39   13575 GOES16  
C2.2 08:56   13576 GOES16  
C2.3 09:32   13576 GOES16  
C2.8 10:43   13576 GOES16  
C3.0 10:48   13576 GOES16  
C2.1 13:00   13576 GOES16  
C4.9 13:41   13576 GOES16  
C2.3 15:04   13576 GOES16  
C2.3 15:33   13574 GOES16  
C2.1 15:58   13574 GOES16  
C2.0 16:35   13576 GOES16  
C2.2 16:59   13574 GOES16  
M1.3 18:06   13576 GOES16 LDE
M1.2 18:19   13576 GOES16  
C4.9 19:02   13575 GOES16  
C2.0 19:50   13576 GOES16  
C3.4 20:25   13576 GOES16  
C2.0 21:37   13574 GOES16  
C2.2 21:58   S9406 GOES16  
C2.1 22:13   13576 GOES16  

Coronal mass ejections (CMEs)

February 5, 7: No obviously Earth directed CMEs were observed.
February 6: A partial halo CME was observed after an M2.2 flare and a long duration M4.2 event peaking at 03:11 UT in AR 13575. A shock wave affected the corona far away from the source. A partial halo CME was associated with this event. The CME was visible in LASCO C2 imagery from 02:36 UT. While the bulk of the CME is not headed for Earth, there is a chance of a weak solar wind shock on February 9. A nearly symmetrical full halo CME was observed near noon. While there was a large filament eruption in the northern hemisphere that was suspected as the origin, any CME associated with that event would be unlikely to cause a CME with the observed mass distribution and intensity. The source of the CME is thus likely to have been backsided.

Coronal holes

[Coronal hole history (since October 2002)]
[Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago]

No obvious coronal holes are currently in or near Earth facing positions.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle and high latitudes is fair. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet on February 8. On February 9 there is a chance of weak CME effects associated with long duration events in AR 13575 early on February 6. Quiet to unsettled conditions are likely on February 9-10.

Coronal holes (1) Coronal mass ejections (2) M and X class flares (3)
     

1) Effects from a coronal hole could reach Earth within the next 5 days. When the high speed stream has arrived the color changes to green.
2) Effects from a CME are likely to be observed at Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next 48 hours.

Green: 0-30% probability, Yellow: 30-70% probability, Red: 70-100% probability.

Active solar regions


(Click on image for 2K resolution). 4K resolution. Compare to the previous day's image.
0.5K image

When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue is positive.

Data for all officially numbered solar regions according to the Solar Region Summary provided by NOAA/SWPC, all other regions are numbered sequentially as they emerge using the STAR spot number. Comments are my own, as is the STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers. SWPC data considered to be not sufficiently precise (location, area, classification) are colored red.

Active region SWPC date numbered
STAR detected
Spot count Location at midnight Area Classification SDO / HMI 4K continuum
image with magnetic polarity overlays
Comment
SWPC/
USAF
Magnetic
(SDO)
SWPC STAR Current Previous
2K 1K
13565 2024.01.27
2024.01.28
2     N05W68 0010 BXO     spotless
13564 2024.01.28 3     S13W83 0040 CAO       there are no spots at that position
13567 2024.01.28
2024.01.30
  6 3 N17W49 0015   AXX

location: N20W40

13570 2024.01.30
2024.02.01
  4 2 S03W35 0013   BXO

location: S02W32

13572 2024.01.31
2024.02.01
2 4 1 S12W61 0010 BXO CRO

area: 0013

13571 2024.01.31
2024.02.01
5 8 4 S17W17 0120 HAX CAO

area: 0140

location: S17W16

13575 2024.01.31
2024.02.02
3 3 3 S37W90 0250 CKO DKC beta-delta

reversed polarities

location: S37W84

area: 0280

13573 2024.02.01
2024.02.01
      N21W75        

location: N21W72

13574 2024.02.01
2024.02.01
3 10 6 N17W08 0020 CRO CRO

area: 0040

location: N17W05

reversed polarities

S9395 2024.02.01       N26W58            
13577 2024.02.02
2024.02.05
4 11 6 N25W07 0010 BXO CRO area: 0040

location: N24W03

13576 2024.02.03
2024.02.03
37 96 59 S16E33 0670 FKC FKC beta-gamma-delta

area: 0990

location: S15E29

S9401 2024.02.04   6 2 S20W02 0008   BXO  
13578 2024.02.04
2024.02.05
4 15 7 S04E41 0030 CRO CRO

area: 0035

reversed polarities

S9403 2024.02.04       S07W22            
S9404 2024.02.05   3 2 S14W74 0080   HAX  
S9405 2024.02.05       N39E33          
S9406 2024.02.06       N12E58          
S9407 2024.02.06   2   S16W57 0003   BXO  
S9408 2024.02.06   8 4 S10E48 0040   DRO  
S9409 2024.02.07   1 1 S21E83 0150   HSX    
13579 2024.02.07 1     S14E60 0050 HAX       not sure what SWPC has observed, there are no spots at or near that location
Total spot count: 64 177 100  
Sunspot number: 164 317 230  (total spot count + 10 * number of spotted regions)
Weighted SN: 105 227 150  (Sum of total spot count + classification weighting for each AR. Classification weighting: X=0, R=3, A/S=5, H/K=10)
Relative sunspot number (Wolf number): 180 174 184  

Monthly solar cycle data

Month Average solar flux International sunspot number
(WDC-SILSO)
Smoothed sunspot number (4) Average ap
(3)
Measured 1 AU
2014.02 170.3
(cycle peak)
166.3 146.1 (SC24 peak) 110.5 10.70
2014.04 143.9 144.8 112.5 116.4 (SC24 solar max) 7.88
2017.09 91.3 92.3 43.6 18.2 (-1.3) 18.22
(SC24 peak)
2019.11 70.2 68.7 0.5 2.0 (-0.6)
(Solar minimum using 365d smoothing:
November 17, 2019)
4.19
2019.12 70.8 68.6 1.6 1.8 (-0.2)
(ISN 13 months smoothed
solar minimum)
3.22
2022.06 116.1 119.8 70.3 81.1 (+3.7) 8.20
2022.07 125.4 129.5 91.4 86.7 (+5.6) 9.51
2022.08 114.2 117.1 74.6 92.6 (+5.9) 10.92
2022.09 135.1 136.5 96.0 96.5 (+3.9) 12.18
2022.10 133.5 132.7 95.5 98.9 (+2.4) 11.16
2022.11 123.4 120.7 80.5 101.2 (+2.3) 9.33
2022.12 147.9 143.4 112.8 106.7 (+5.5) 10.99
2023.01 182.4 176.6 144.4 113.3 (+6.6) 8.73
2023.02 167.2 163.2 111.3 117.8 (+3.5) 14.48
(current
SC25 peak)
2023.03 157.2 155.6 123.3 121.1 (+3.3) 14.42
2023.04 145.4 146.4 97.6 122.9 (+1.8) 13.40
2023.05 155.6 159.2 137.4 124.1 (+1.2) 10.67
2023.06 161.7 166.8 160.5 125.2 (+1.1)
(SC25 solar max candidate)
8.95
2023.07  176.4 182.2 160.0 124.3 (-0.9) 8.15
2023.08  153.7 157.6 114.8 (123.4 projected, -0.9) 7.19
2023.09  154.4 156.0 134.2 (123.1 projected, -0.3) 14.26
2023.10  142.8 141.9 99.4 (123.9 projected, +0.8) 8.16
2023.11 153.5 150.2 105.4 (123.9 projected, +0.0) 12.20
2023.12 151.1 146.4 114.2 (120.5 projected, -3.4) 9.60
2024.01 164.6 159.3 123.0 (117.1 projected, -3.3) 5.46
2024.02 163.9 (1)   34.7 (2A) / 143.7 (2B) / 167.6 (2C) (116.3 projected, -0.8) (4.3)
2024.03       (115.8 projected, -0.5)  
2024.04       (115.7 projected, -0.1)  
2024.05       (117.0 projected, +1.3)  
2024.06       (116.2 projected, -0.8)  
2024.07       (114.5 projected, -1.7)  

1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz and any corrections applied to that measurement.
2A) Current impact on the monthly sunspot number based on the Boulder (NOAA/SWPC) sunspot number (accumulated daily sunspots / month days).
2B) Boulder SN current month average to date.
2C) STAR SDO 1K Wolf number 30 day average.
3) Running average based on the quicklook and definitive Potsdam WDC ap indices. Values in red are based on the definitive international GFZ Potsdam WDC ap indices.
4) Source: WDC-SILSO, Royal Observatory Of Belgium, Brussels

Solar cycles 24-25

Smoothed SF and sunspot numbers

Update on the progress of solar cycle 25 as of January 3, 2024

The relatively low solar activity during the last months of 2023 significantly increased the possibility that solar cycle 25 has already peaked. Whether the first peak in June 2023 will be the actual solar max will not be known for some time. Due to the relatively high solar activity early in 2023 it is unlikely there will be another solar max candidate, if at all, until at least May 2024. Both the northern and southern polar fields, as well as the averaged total field, have already reversed polarities.

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This report has been prepared by Jan Alvestad. It is based on the analysis of data from whatever sources are available at the time the report is prepared. All time references are to Universal Time. Comments and suggestions are always welcome.

SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.